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🌬️ Topic I: Respiratory System
🔑 Key Terms
* Respiration: The process by which cells break down glucose with oxygen to release energy (ATP).
* Gas Exchange: The transfer of oxygen into the blood and carbon dioxide out, occurring in the alveoli.
🛤️ Respiratory Pathway (Air Passage Route)
Nostrils → Nasal Cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli
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🫁 Structure and Function Overview
Part
Function
Nasal Cavity
Air entry; warms, moistens, and filters air using fine hairs and mucus
Septum
Divides the nasal cavity
Fine Hairs (Cilia)
Trap particles and pathogens
Mucous Membrane
Moistens air and traps dust
Pharynx
Passage for both air and food
Epiglottis
Prevents food from entering the trachea during swallowing
Larynx (Voice Box)
Contains vocal cords; sound production
Thyroid Cartilage
Protects the vocal cords
Trachea
Windpipe; has cartilaginous rings to stay open; lined with cilia
Main Bronchi
Two branches from trachea entering each lung
Bronchioles
Smaller branches of bronchi
Alveoli
Site of gas exchange
Pleura
Double membrane surrounding lungs
Lungs
Contain bronchi, bronchioles, and alveoli
Diaphragm
Main muscle for breathing
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🔄 Breathing Mechanics
* Inhalation: Diaphragm contracts (moves down), chest cavity enlarges, air enters lungs.
* Exhalation: Diaphragm relaxes (moves up), chest cavity reduces, air is pushed out.
⚙️ Gas Exchange Process
* Oxygen moves from alveoli → capillaries → bloodstream
* Carbon dioxide moves from blood → alveoli → exhaled
🚨 Hyperventilation
* Excessive breathing reduces CO₂ levels → dizziness, tingling
* Can lead to respiratory alkalosis (blood becomes too basic)
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🚽 Topic II: Excretory System
🧬 What is Excretion?
Removal of metabolic wastes (e.g., urea, water, salts) to maintain homeostasis.
🔄 Main Waste Products
* Urea (from protein metabolism)
* Water & Mineral Salts
* Bile Pigments (from hemoglobin breakdown)
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🧠 Urine Formation Pathway
Kidneys → Ureters → Urinary Bladder → Urethra
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🏥 Kidney Structure & Function
Region
Function
Cortex
Outer layer, contains nephrons
Medulla
Middle layer, contains pyramids
Renal Pyramids
Transport urine into pelvis
Renal Pelvis
Collects urine for ureter
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🧪 Nephron Anatomy
Part
Function
Malpighian Corpuscle
Filters blood
Bowman’s Capsule
Encloses the glomerulus (initial filtration)
Convoluted Tubules
Reabsorb useful substances; secrete wastes
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💧 Urine Formation Steps
1. Filtration: In glomerulus; blood plasma enters Bowman’s capsule
2. Reabsorption: Water, glucose, salts reabsorbed in tubules
3. Secretion: Toxins added to filtrate before urine exits
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❤️🩹 Topic III: Cardiovascular System & Hematology
🫀 Heart Anatomy
Part
Function
Endocardium
Inner lining
Myocardium
Thick cardiac muscle layer
Epicardium
Outer surface layer
Pericardium
Protective sac
Septum
Divides left and right halves
💓 Heart Chambers & Valves
* Atria: Receive blood (Right from body, Left from lungs)
* Ventricles: Pump blood out (Right to lungs, Left to body)
* Atrioventricular Valves: Tricuspid (right), Bicuspid/Mitral (left)
* Semilunar Valves: Aortic and pulmonary valves
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🌍 Circulatory Circuits
* Pulmonary Circuit: Right heart → lungs → left heart
* Systemic Circuit: Left heart → body → right heart
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🔄 Cardiac Cycle
* Systole = Contraction (blood pumped)
* Diastole = Relaxation (chambers refill)
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🩸 Blood Vessels
Vessel
Function
Arteries
Carry blood away from heart
Capillaries
Gas/nutrient exchange
Veins
Return blood to heart
Coronary arteries: Supply heart muscle with oxygen.
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🧬 Blood Composition
Component
Function
Plasma
Liquid portion; contains water, proteins (e.g. fibrinogen)
RBCs (Erythrocytes)
Carry oxygen (oxyhemoglobin); no nucleus; biconcave shape
WBCs (Leukocytes)
Fight infection (lymphocytes, monocytes, phagocytes)
Platelets (Thrombocytes)
Aid in clotting
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💉 Lymphatic System
* Lymph: Fluid that filters through tissues
* Lymph Nodes: Filter lymph and trap pathogens
* Tissue Fluid: Bathes cells; part of lymphatic return system
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🧬 Blood Groups & Immunity
System
Key Points
ABO System
A, B, AB, O blood types; antigen-antibody compatibility
Rh System
Rh+ or Rh–; important in pregnancy and transfusions
Immunity
Body’s defense; vaccines stimulate antibody production
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🧠 Topic IV: Endocrinology
🧬 Endocrine System Overview
* Endocrine Glands: Ductless; secrete hormones into blood
* Hormones: Chemical messengers acting on target organs
* Hyperfunction: Overproduction
* Hypofunction: Underproduction
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🧠 Pituitary Gland (“Master Gland”)
Hormone
Function
TSH
Stimulates thyroid
ACTH
Stimulates adrenal cortex
Gonadotropins
Regulate ovaries/testes
Somatotropin
Growth hormone
ADH
Water balance (kidney)
Oxytocin
Childbirth, milk release
Disorders: Gigantism, dwarfism, acromegaly, cachexia
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🌙 Pineal Gland
* Melatonin: Controls sleep-wake cycles (circadian rhythm)
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🦋 Thyroid & Parathyroids
Hormone
Function
Thyroxine
Regulates metabolism
Parathormone
Regulates calcium levels
Disorders:
* Goitre (iodine deficiency)
* Cretinism (infant hypothyroidism)
* Hyperthyroidism, Hypothyroidism (Myxoedema)
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🛡️ Thymus
* Thymosin: T-cell development; active in children
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🍬 Pancreas (Heterocrine)
* Insulin: Lowers blood sugar
* Glucagon: Raises blood sugar
* Disorder: Diabetes mellitus
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⚡ Adrenal Glands
* Adrenaline/Noradrenaline: “Fight or flight” response (stress hormones)
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♀️♂️ Gonads
Gland
Hormones
Function
Testes
Testosterone
Male traits, sperm production
Ovaries
Folliculin, Estrogen, Progesterone
Female traits, menstrual cycle
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✅ Study Tips
* Use diagrams: Label parts of systems (heart, kidney, alveoli, etc.)
* Practice flowcharts: Respiratory, circulatory, urinary pathways
* Compare disorders: Especially for endocrine diseases
* Quiz yourself: On hormone functions and anatomical parts
* Use mnemonics: For remembering sequences and functions
Let me know if you want flashcards, quiz questions, or visual diagrams next!